Rulings

[Insane Blue]

Here is how I would rule without looking in the rulebook..

Sit. 1 S5 is back to serve. As she contacts the serve a ball from another court rolls onto the court and under the net. The R1 stops play and signals for a replay, Team B then executes a libero replacement.
legal replacement as the ball is whistled dead and you have a replay.

Sit 2 S5 is back to serve. After she hits the ball, R2 signals the Team R out of rotation, and the ball fails to cross the net legally. Team R's coach questions the call and the R2 realizes his call was incorrect. What's the call?
Replay as the ref killed the play before the ball hit the ground.

Sit 3. S5 tosses the ball to serve and swings and misses. Team R then executes a libero replacement. What's the call?
Illegal as this is a reserve and the beckon from the first serve means no Subs until the play finishes.